Magnetoresistive Sensor ICs
Standard Power Series: SM351RT, SM451R, SM353RT, SM453R
32304118
Issue C
Datasheet
SM451R
SM453R
SM351RT
SM353RT
DESCRIPTION
Honeywell’s Magnetoresistive Sensor ICs (integrated circuits),
Standard Power Series, are ultra-sensitive devices designed
for manufacturers who need a durable and reliable speed or
position sensor for large air gaps or small magnetic fields in
standard power (typically 3 Vdc to 24 Vdc) applications. Unlike
reed switches and other magnetic sensors, Honeywell’s solid
state design offers ultra-high sensitivity of 11 G max., making it
the highest sensitivity sensor in its class for standard powered
applications. The Magnetoresistive Sensor ICs, Standard Power
Series, respond to either a North or South pole applied in a
direction parallel to the sensor. They do not require the magnet
polarity to be identified, simplifying installation and potentially
reducing system cost.
VALUE TO CUSTOMERS
• Durable and reliable due to magnetic solid state, non-contact,
no-glass design which enhance switching capability.
• Cost-effective and flexible due to the sensor IC’s ultra-high
sensitivity—the highest sensitivity sensor in its class for
standard powered applications—which lowers the customer’s
cost of magnets and simplifies design-in.
• Simplifies design-in for wired applications due to its supply
voltage range, omnipolar operation, SOT-23 and flat TO-92-
style package options and wide operating temperature range.
DIFFERENTIATION
•
Ultra-high sensitivity (SM351RT and SM451R) allows for
potential use in applications requiring ultra-high magnetic
sensitivity (7 G typical operate, 11 G maximum operate).
FEATURES
• Magnetic sensitivities:
- Ultra-high sensitivity (SM351RT and SM451R): For
applications requiring ultra-high magnetic sensitivity
(7 G typical operate, 11 G maximum operate)
- Very high sensitivity (SM353RT and SM453R): For
applications requiring very high magnetic sensitivity
(14 G typical operate, 20 G maximum operate)
• Package styles:
- SOT-23 (SM351RT, SM353RT)
- Flat TO-92-style (SM451R, SM453R)
• Supply voltage range 3 Vdc to 24 Vdc
• Omnipolar sensing activates with either pole from a magnet
• Temperature range -40 °C to 85 °C [-40 °F to 185 °F]
• SOT-23 supplied on tape and reel (3000 units per reel)
• RoHS-compliant materials meet Directive 2002/95/EC
POTENTIAL APPLICATIONS
Industrial
• High frequency flow sensing in HVAC, water, fuel meters,
and gas utility meters
• Anti-tamper detection in water, electric, and gas utility
meters
• Liquid level detection
• Motor RPM sensing
• In-cylinder position sensing
Medical
• RPM sensing in exercise and rehabilitation equipment
• Magnetic interrupt in exercise and rehabilitation equipment
• Absence/presence detection in infusion pumps
• Position sensing of medication dispensing cabinet drawers
• Incline position sensing in hospital beds
White Goods
• Lid, door and drawer position detection
• Fluid flow detection
• Liquid level detection
PORTFOLIO
Honeywell’s Standard Power Series join:
• Magnetoresistive sensor ICs, including the
Nanopower
Series, 2SS52M Series, SS552MT Series
• Hall-effect sensor ICs, including the
SS351A, SS451A
Sensing and Productivity Solutions
Magnetoresistive Sensor ICs
CCharacteristic
Supply voltage (Vcc)
Supply current:
off
on
Start-up time
Output leakage current
Output saturation voltage
Rise time
Fall time
Standard Power Series: SM351RT, SM451R, SM353RT, SM453R
Table 1. Electrical Specifications (3 V < Vcc < 24 V, -40 °C < Ta < 85 °C [-40 °F < Ta < 185 °F] unless otherwise specified.)
Condition
Vcc reference to ground
—
Vcc = 5 V, T = 25 °C [77 °F]
Vcc = 5 V, T = 25 °C [77 °F
Vcc > 3 V
Vcc = 24, off
load current = 20 mA
Vcc = 5 V, R = 2 kOhm, C = 20 pF
Vcc = 5 V, R = 2 kOhm, C = 20 pF
Min.
3
—
—
—
—
—
—
—
Typ.
12
2.5
4
—
—
—
—
—
Max.
24
8
3.5
5
10
10
500
1.5
1.5
Unit
V
mA
µs
µA
mV
µs
Table 2. Magnetic Specifications (3 V < Vcc < 24 V, -40 °C < Ta < 85 °C [-40 °F < Ta < 185 °F].
)
Characteristic
SM351RT, SM451R:
operate (positive)
release (positive)
differential
SM353RT, SM453R:
operate (positive)
release (positive)
differential
Min.
3
2
—
Typ.
7
4.8
2.2
Max.
11
9
—
Unit
Gauss
6
3
—
14
9.3
5.7
20
18
—
Gauss
NOTICE
The magnetic field strength (Gauss) required to cause the switch
to change state (operate and release) will be as specified in the
magnetic characteristics. To test the switch against the specified
magnetic characteristics, the switch must be placed in a uniform
magnetic field.
NOTICE
These magnetoresistive sensor ICs may have an initial output in
either the ON or OFF state if powered up with an applied magnetic
field in the differential zone (applied magnetic field >Brp and
<Bop). Honeywell recommends allowing 10 μs for output voltage
to stabilize after supply voltage has reached its final rated value.
Table 3. Absolute Maximum Ratings
C
Characteristic
Operating temperature
Soldering temperature:
SM351RT, SM353RT
SM451R, SM453R
Supply voltage (Vs)
Load current
Condition
ambient
ambient applied for < 10 s
ambient applied for < 3 s
—
output sinking (open collector)
Min.
-40 [-40]
—
—
-26
—
Typ.
—
—
—
—
—
Max.
85 [185]
245 [473]
260 [500]
26
40
Unit
°C [°F]
°C [°F]
V
mA
NOTICE
Absolute maximum ratings are the extreme limits that the device will withstand without damage to the
device. However, the electrical and mechanical characteristics are not guaranteed as the maximum limits
(above recommended operating conditions) are approached, nor will the device necessarily operate at
absolute maximum ratings.
CAUTION
ELECTROSTATIC
SENSITIVE
DEVICES
DO NOT OPEN OR HANDLE
EXCEPT AT A
STATIC FREE WORKSTATION
ESD SENSITIVITY:
CLASS 3A
2
Sensing and Productivity Solutions
Magnetoresistive Sensor ICs
SM351RT, SM451R
Standard Power Series: SM351RT, SM451R, SM353RT, SM453R
Figure 1. Typical Magnetic Performance versus Temperature
10
9
Magnetic Switch Point (Gauss)
8
7
6
5
4
3
2
1
0
-40
[-40]
-20
[-4]
0
[32]
20
[68]
40
[104]
60
[140]
80
[176]
Differential Gauss
Release Gauss
Operate Gauss
Temperature (°C [°F])
SM353RT, SM453R
18.0
Magnetic Switch Point (Gauss)
16.0
14.0
12.0
10.0
8.0
6.0
4.0
2.0
0.0
-40
[-40]
-20
[-4]
0
[32]
20
[68]
40
[104]
60
[140]
80
[176]
Differential Gauss
Release Gauss
Operate Gauss
Temperature (°C [°F])
Figure 2. Block/Electrical Diagram
AMR
Sensor
Trigger
circuit
and
ampli er
Vcc (+)
Output (O)
Gnd (-)
Sensing and Productivity Solutions
3
Magnetoresistive Sensor ICs
Standard Power Series: SM351RT, SM451R, SM353RT, SM453R
Figure 3. Alignment of the Magnet to the SOT-23 Package (SM351RT, SM353RT) Omnipolar Magnetoresistive Sensor IC
Ideal alignment: The magnet is aligned in the same plane as the sensor IC.
The magnetic flux lines stay horizontal as the magnet
approaches the sensor IC (see Figure 3.A)
.
Figure 3.A
SM351RT,
SM353RT
Sensor IC
Magnet
Magnet movement
Offset alignment: The magnet is not aligned in the same plane as the sensor IC.
Parallel magnet approach to the sensor IC may cause dead zones.
Dead zones may occur when the majority of the magnet’s
magnetic flux lines become vertical as it approaches the
sensor IC, turning the sensor IC ON, then OFF, then ON
(see Figure 3.B).
Magnet
Magnet
SM351RT,
SM353RT
Sensor IC
Figure 3.B
Magnet movement
Perpendicular magnet approach to the sensor IC eliminates possible dead
zones.
The sensor IC detects the approaching magnet’s horizontal magnetic flux lines, turning the sensor IC to ON. The sensor IC stays
ON as the magnet continues to approach. When the magnet is located directly over the sensor IC, all magnetic flux lines are now
horizontal (see Figure 3.C). (Note: This alignment decreases the magnetic flux strength at the sensor IC.)
Magnet
SM351RT,
SM353RT
Sensor IC
end view
Figure 3.C
top view
Magnet movement
4
Sensing and Productivity Solutions
Magnetoresistive Sensor ICs
Standard Power Series: SM351RT, SM451R, SM353RT, SM453R
Figure 4. Alignment of the Magnet to the TO-92-Style Package (SM451R, SM453R) Omnipolar Magnetoresistive Sensor IC
Ideal alignment: The magnet is aligned in the same plane as the sensor IC.
The magnetic flux lines stay horizontal
as the magnet approaches the sensor
IC (see Figure 4.A)
.
Figure 4.A
SM451R,
SM453R
Sensor IC
Magnet
Magnet movement
Offset alignment: The magnet is not aligned in the same plane as the sensor IC.
Parallel magnet approach to the sensor IC may cause dead zones.
Dead zones may occur when the majority
of the magnet’s magnetic flux lines become
vertical as it approaches the sensor IC,
turning the sensor IC ON, then OFF, then
ON (see Figure 4.B).
Figure 4.B
Magnet
SM451R,
SM453R
Sensor IC
Magnet movement
Perpendicular magnet approach to the sensor IC eliminates possible dead zones.
The sensor IC detects the approaching magnet’s horizontal magnetic flux lines, turning the sensor IC to ON. The sensor IC stays
ON as the magnet continues to approach. When the magnet is located directly over the sensor IC, all magnetic flux lines are now
horizontal (see Figure 4.C). (Note: This alignment decreases the magnetic flux strength at the sensor IC.)
Magnet
SM451R,
SM453R
Sensor IC
end view
Figure 4.C
top view
Magnet movement
Sensing and Productivity Solutions
5
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